This wavform arm contains no subsetters. The phaseRequest
specifies that a request should be made for data from
120 seconds before the P wave arrival to 3 minutes after the S wave arrival. fixedDataCenter
tells SOD to fetch
that data from IRIS's FDSN DataSelect web service. The printlineSeismogramProcess prints
information about each seismogram it retrieves.

The previous recipe gets data for every channel, for every earthquake that SOD finds.
Adding this subsetter to the waveform arm tells SOD
to process only channels that are 30 to 90 degrees away from an earthquake. In this image, the triangles
are channels and the earthquake is at the center of the shadowed ring.
SOD only processes those channels outlined in green.

In nearly all cases you'll only want to process when the server has data. When you insert a
someCoverage tag after specifying the server, SOD asks the server if there is data
before making the request to retrieve it. Unfortunately sometimes servers
don't actually know what they have, and so it can be useful to use the
someDataCoverage as well that checks after asking for the seismograms that they really
exist.

In addition to the subsetting and data gathering steps of the waveform arm, SOD has a suite of
data processing ingredients. These ingredients go at the end of the waveform arm and operate on the
seismograms one after another.

The above snippet will:

Print a line for each seismogram

Save the raw seismogram as SAC files

Apply a gain correction to the seismogram

Remove the mean from the seismogram

Remove the trend from the seismogram

Integrate the seismogram, ie changes velocity to displacement

Save the processed results as another set of SAC files in the processedSeismograms directory

Execute the echo command with the file names from the save

You can include any number of these processing tasks in a recipe. You can also add subsetters between processors
if you wish to conditionally process seismograms. In addition to processors in the snippet above,
SOD contains processors
to filter seismograms, produce images, and taper seismograms among others.
You can find the full list of processors in the
seismogramProcess page in the
ingredient listing.